Influence of Residue Soil on the Properties of Fly Ash-Slag-Based Geopolymer Materials for 3D Printing.

This study investigates the impact of residue soil (RS) powder on the 3D printability of geopolymer composites based on fly ash and ground granulated blast furnace slag. RS is incorporated into the geopolymer mixture, with its inclusion ranging from 0% to 110% of the combined mass of fly ash and finely ground blast furnace slag. Seven groups of geopolymers were designed and tested for their flowability, setting time, rheology, open time, extrudability, shape retention, buildability, and mechanical properties. The results showed that with the increase in RS content, the fluidity of geopolymer mortar decreases, and the setting time increases first and then decreases. The static yield stress, dynamic yield stress, and apparent viscosity of geopolymer mortar increase with the increase in RS content. For an RS content between 10% and 90%, the corresponding fluidity is above 145 mm, and the yield stress is controlled within the range of 2800 Pa, which meets the requirements of extrusion molding. Except for RS-110, geopolymer mortars with other RS contents showed good extrudability and shape retention. The compressive strength of 3D printing samples of geopolymer mortar containing RS has obvious anisotropy.